1. Field of the Invention
The present invention relates to a tape transport monitoring device of a tape player which detects the end of a tape by detecting rotation of a pair of reels for taking up a tape, more particularly, to a tape, transport mechanism which is capable of automatically adjusting, at the tape-takeup end and the tape-feeding end, the torque of the reel blocks and a detecting portion for actuating tape end detecting means.
2. Description of the Prior Art
As described, for example, in Japanese Patent Publication No. 145749/1986, a conventional tape player of this type has a pair of reel blocks for taking up a tape, rotary disks in friction contact with the pair of reel blocks and rotated together with them, a rotation detection arm oscillated by rotation of the rotary disks, and tape end detecting means for detecting a tape end by detecting the cessation of oscillation of the rotation detection arm. Rotation of the reel blocks stops when a tape has been taken up to the end so that the rotation detection arm, which is rotated by the rotary disk in friction contact with the reel block at the tape-takeup end, ceases to rotate, thereby actuating the tape end detecting means. According to this conventional structure, tension of the reel blocks at the tape-takeup end and the tape-feeding end are identical, hence tension of the rotary disks rotated by means of friction contact with their respective reel blocks, are identical.
With a tape player having the above conventional structure, wherein rotary disks rotated by friction contact with the reel block at the tape-takeup end and the reel block at the tape-feeding end respectively have identical torques, unless considerable pressure is applied to the rotation detection arm which is connected through friction to the reel block at the tape-takeup end, it is not possible to actuate the rotation detection arm to detect a tape end at the tape-takeup end. However, if the rotation torque of the rotary disk at the tape-feeding end, which is in frictional contact with the reel block at the tape-feeding end, is identical to that of the other torque, it makes the rotation torque at the tape-feeding end excessively large. As a result, when a button or switch is operated to actuate the fast forward or fast rewind operation, the operation is not always conducted smoothly due to back tension at the tape-feeding end, which causes uneven transport of the tape. On the other hand, in cases where there is no or little back tension at the tape-feeding end, a tape may slacken and be caught between a pinch roller and a capstan, thereby making detection of the tape end impossible.
In order to solve the above problems, the present invention has as its object the provision of a tape transport mechanism of a tape player which is capable of automatically switching the magnitude of the torque so that the torque of the reel block at the tape-takeup end and the rotary disk corresponding thereto is always greater than the torque of the reel block feeding out the tape and the rotary disk corresponding thereto. This ensures detection of a tape end, and conveys a tape evenly in the fast forward mode with the absolute minimum necessary back tension at the tape-feeding end.